Response of wheat varieties to different zinc application methods

An experiment on response of different wheat varieties to zinc application methods was evaluated at Agriculture University Peshawar Pakistan in 2016-17. The experimental design was RCB with 3 replications. Zinc application methods (control, 1% foliar with ZnSO4, 1% priming with ZnSO4, 15 kg ha soil application, 1% foliar with ZnSO4 + 1% priming with ZnSO4, 1% foliar with ZnSO4 + 15 kg ha Zn application to soil, 1% priming with ZnSO4+ 15 kg ha Zn soil application, 1% foliar with ZnSO4 +1% priming with ZnSO4 +15 kg ha -1 Zn soil application) & varieties (Atta Habib & Zincol) were used in the experiment. Plant height, spike m, grains spike, 1000 seed weight, biological yield and grain yield showed significant response to zinc application methods and varieties. Taller plant (98.8 cm), spikes m (358), grains spike (57), 1000 seed weight (49.1 g), biological yield (10067 kg ha) and grain yield (4319.3 kg ha) were recorded in plots treated with 1% foliar with ZnSO4 + 1% priming with ZnSO4 + 15 kg ha -1 Zn soil application of ZnSO4. Considering wheat varieties plant height (94 cm), tillers m (317), spikes m (301), grains spike (52), biological yield (9073.3 kg ha) and grain yield (4103.5 kg ha) recorded from Zincol. It is concluded that Zincol wheat variety with application of 1% foliar with ZnSO4 + 1% priming with ZnSO4 + 15 kg ha -1 Zn soil application of ZnSO4 performed better in terms of yield and thus recommended for general cultivation.


Introduction
In cereals wheat is the most important crop worldwide.Among wheat producing countries Pakistan ranks 8 th , contributes almost 3.17% wheat production of the world.In Pakistan wheat crop is a leading food grain and occupies central position in economy.In Pakistan during 2015-16 wheat is cultivated on about 8.66 million hectares with total production of 23.517 million tons [1].While in Khyber Pakhtunkhwa it was cultivated on 0.758 million hectares with average production of 1607.5 kg ha -1 .Wheat, as a food crop is mostly used for its good taste and source of calories, proteins and vitamins.Low quality of wheat and flour-milling by-products are used as source of feed for livestock.Micronutrients are used for growth and regulation of plant's vital physiological processes.They are necessary in low amounts, but equally important like macronutrients [2].Deficiency of micronutrients in Pakistan is due to calcareous soils, high pH, low organic matter, salt stress and imbalanced application of NPK fertilizers [3].Zinc is one of the most important micronutrient in biological zones and is receiving more attention throughout world [4,5].Deficiency of Zn affects about 1/3 of the total world's populations [6,7].In soils due to low dissolvability of Zn plant cell growth reduction and development is one of the Zn deficiency symptom [8].In human beings Zn deficiency is very common especially in those countries with high consumptions of cereal-based foods.Therefore, there is a great need to improve cereal crops with adequate Zn nutrition.Deficiency of Zn is also a critical constraint to wheat production.In cereals based cultivated soils all over the world it is widely accepted that deficiency of Zn in soil is the most commonly occurring micronutrient deficiency.The unavailability of soil Zn resulting in severe losses in terms of economic and decreased plant growth and yield production.Factor B; Wheat Varieties, V1=Atta Habib, V2=Zincol.All the treatment combinations were randomly allotted to the experimental units using randomized complete block design with 3 replications.Plot size was maintained 3m x 3m.For foliar application and Zn priming, 1% solution from ZnSO4.7H2O source was prepared.The solution was diluted with water while keeping in view the treatments and volume to wet the plot area completely.The foliar Zn treatment was applied in the late afternoon within different growth stages.Wheat varieties Atta Habib and Zincol were sown at the rate of 120 kg ha -1 with 30cm R-R distance.The nitrogen and phosphorus was applied at the rate of 120 kg ha -1 and 90 kg ha -1 .Urea and DAP was used as a source of nitrogen and phosphorous.All of the phosphorous and half dose of nitrogen was applied at sowing time and the remaining dose was applied later at 2 nd irrigation.All other agronomic practices were kept normal and uniform for all the treatments.

Statistical analysis
Data was statistically analyzed [13] and means were computed using LSD test (P < 0.05).

Plant height (cm)
Data on plant height of wheat as influenced by different zinc application methods and varieties are given in (Table 1).The data shows that zinc application methods and varieties shows significant affect plant height of wheat.Highest plant height (98.8 cm) was recorded in plots which were treated with 1% foliar + 1% priming + 15 kg ha -1 soil application while the lowest was recorded with no zinc application.Similarly taller plants (94 cm) were recorded for Zincol and short stature plants were recorded for Atta Habib (91 cm).V x Zn was found non-significant.

Number of productive tillers (m -2 )
Table 1 shows data on number of productive tillers per m 2 of wheat as influenced by different zinc application methods.The data shows that zinc application methods and varieties significantly affected number of productive tillers m -2 of wheat.More number of productive tillers m -2 (368) were observed in plots which were treated with 1% foliar + 1% priming + 15 kg ha -1 soil application while lower (281) were recorded with no zinc application.In case of varieties maximum number of tillers per m 2 was recorded for Zincol (317) and lower were recorded for Atta Habib (313).The interaction of v x Zn was found nonsignificant.2).The data shows that zinc application methods and varieties significantly response to biological yield of wheat.More biological yield (10067 kg ha - 1 ) was recorded in plots which were treated with 1% foliar + 1% priming + 15 kg ha -1 soil application while least (7721 kg ha -1 ) was recorded with no zinc application.Higher biological yield (9073 kg ha -1 ) was recorded for Zincol and lower (8728 kg ha - 1 ) was recorded for Atta Habib.The combined effect of V x Zn was found nonsignificant.Grain yield (kg ha -1 ) Data of grain yield of wheat as influenced by various zinc application methods and varieties are present in (Table 2).The data on grain yield of wheat shows significant response to zinc application method and varieties.More grain yield (4319 kg ha -1 ) was recorded in those plots which were treated with 1% foliar + 1% priming + 15 kg ha -1 soil application while lower (3771 kg ha -1 ) was recorded with no zinc application.More grain yield (4103 kg ha - 1 ) was recorded for Zincol and lower (3890 kg ha -1 ) was recorded for Atta Habib.The interaction of V x Zn was found significant.

Harvest index (%)
The impact of different zinc application methods and varieties on harvest index of wheat is shown in ( [19] Also reported that Zinc application significantly increased thousand grains weight of wheat varieties.Biological yield of wheat was significantly affected by different zinc application methods.More biological yield was recorded in plots which were treated with 1% foliar + 1% priming + 15 kg ha -1 soil application while least was recorded in no Zinc application.The reason for increase in biological yield might be that zinc application increased vegetative growth of the plant which resulted in greater biomass accumulation.Our results are in line with the result of [11] who reported that the unavailability of zinc may contribute to growth reduction in terms of lesser biomass production.More biological yield was recorded for Zincol and less was recorded for Atta Habib.The probable reason for the better response is that different varieties respond differently to zinc application method.Grain yield of wheat varieties was affected by different application methods of zinc More grain yield was recorded with 1% foliar + 1% priming + 15 kg ha -1 soil application method while less was recorded with no zinc application.Higher grain yield was oberved for Zincol and least was recorded for Atta Habib.This might be due to the fact that different varieties have different genetic make-up and hence respond differently to different zinc application method.[22] Also reported that zinc application methods increased the grains yield of wheat significantly.The different zinc application methods showed significant impact on harvest index of wheat.Higher harvest index was recorded at 15 kg h -1 soil application while minimum was recorded in those plots where 1% priming with ZnSO4 + 15 kg ha - 1 soil application was applied.Our results are in line with those of [23] who reported maximum harvest index for higher dose of zinc.While varieties showed nonsignificant impact on harvest index.

Conclusion
It is concluded from the above finding that Zinc application method of 1 % foliar + 1 % priming + 15 kg ha -1 soil Zn application produced higher grain yield of wheat.Zincol variety produced more productive tiller m -2 , spike per m 2 , and 1000 seed weight, grains spike -1 and grain yield as compared to Atta Habib.Variety Zincol and Zinc application method consisting of 1 % foliar with ZnSO4 + 1% priming with ZnSO4 + 15 kg ha -1 soil application is recommended for achieving maximum yield and yield components of wheat.

Authors' contributions
Conceived and designed the experiments: N Aziz & S Anwar, Performed the experiments: N Aziz, Analyzed the data: N Aziz, S Anwar & J Ahmad, Contributed materials/ analysis/ tools: S Kashmir, B